Conventionally, server systems and storage systems in data centers and hospitals adopt a UPS (Uninterruptible Power Supply), which enables the systems to continue operation even during power failure or other external power supply failures. Actually, the system can be operated continuously by starting an internal power generating device during continuous operation using the UPS.
Further, regarding the art related to failure correspondence, an art is disclosed where control is performed in response to the type of the data stored in a cache memory or the remaining battery power when external power supply is cut off due to failure, to thereby protect the data in the cache, which is a volatile memory, while reducing the power consumption of the battery power supply. However, according to the conventional system adopting the UPS, there was a drawback in that the costs of the batteries used for the UPS and the installation costs were high.
Even further, there were cases where the system could not be stopped safely when there were no internal power generating device installed in the system, or when it was assumed that the stopping of the power supply will continue for a long time. Patent Literature 1 discloses an art corresponding to such problems. The disclosed art provides a computer capable of stopping the system safely and with a low cost. Actually, the computer includes a nonvolatile memory for storing data, a control processor for controlling the saving of data to the nonvolatile memory, and a battery for supplying power to the computer when failure occurs to an external power supply, which is characterized in that a control processor confirms a charged quantity of power accumulated in the battery, computes based on the confirmed charged quantity the amount of data savable to a nonvolatile memory using the battery when failure occurs to the external power supply, and saves the amount of data excluding the savable data quantity from the data to be saved to the nonvolatile memory in advance to the nonvolatile memory.